SarcoidosisDefinition: Sarcoidosis may involve any of a number of ocular tissues, including the conjunctiva. Conjunctival disease manifests small, tan nodules primarily within the fornix and tarsal regions.
Incidence/Prevalence: Sarcoidosis affects men and women of all races and ages. The condition usually presents in adults younger than 40 years, most frequently between 20 and 29 years of age. It is slightly more predominant in women than in men, with an incidence of 6.3 and 5.9 cases per 100,000 person-years, respectively. The lifetime risk of sarcoidosis for U.S. "whites" is estimated at 0.85 percent compared with 2.4 percent in U.S. "blacks". Sarcoidosis is most prevalent in Swedes, Danes, and U.S. blacks. Caution is advised in interpreting these figures as genetic studies have demonstrated that the U.S. population is much more heterogeneous with mixed ethnicity than previously realized. The artificial "racial" divisions are probably not warranted and may obfuscate understanding the etiology of the disease.
Etiology: Sarcoidosis is a multisystem granulomatous disease with an unknown etiology, characterized by the presence of non-caseating granulomas in involved organs.
Clinical Findings: Systemic sarcoidosis may present with bilateral hilar lymphadenopathy, pulmonary infiltrates, and ocular and skin lesions. The heart, liver, spleen, salivary glands, muscles, bones, kidneys, and central nervous system also may be involved.
Serum and tear levels of angiotensin converting enzyme are elevated. Conjunctival lesions often present as elevated nodules, single or multiple, of the palpebral surfaces. The lesions are yellow or tan in color and do not exhibit necrosis.
Histopathology: Histopathologically, non-caseating granulomas (aggregates of epithelioid histiocytes) may be present in the substantia propria. A minimal cuff of lymphocytes and plasma cells surround the lesions. Multinucleated giant cells may or may not be present within the granuloma. Star shaped asteroid bodies and calcific Schaumann bodies may be seen in epithelioid cells and particularly multinucleated cells but are not specific for sarcoidosis. Often one is faced with the random biopsy of conjunctiva in search of a granuloma of sarcoid. This procedure may be effective but the yield is exceedingly low in most hands despite step sectioning the entire tissue. Performing multiple (map biopsies) bilaterally will improve the yield. (1) Clinically performed confocal microscopy may be a more effective way to delineate tissue that is abnormal for biopsy. (2)
The diagnosis of sarcoidosis is one of exclusion from a pathologic standpoint; the diagnosis of sarcoidosis cannot be made on histologic grounds alone. Infectious etiologies of granulomatous disease include bacteria such as Francisella tularensis (tularemia) and Bartonella henselae (cat-scratch disease), mycobacteria, fungi, spirochetes, or parasites. Foreign body granuloma can usually be excluded if produced by suture and wood because they polarize light and can be viewed with 2 polarizing filters placed above the slide and below the substage condenser.
Treatment: Corticosteroids remain the mainstay of treatment. Methotrexate and antimalarial agents are also used in certain scenarios of the clinical disease.
Prognosis: The prognosis of systemic disease has some correlation with mode of onset, host characteristics, initial clinical course, and extent of disease. Mortality from sarcoidosis, usually respiratory failure, is between 1 and 5 percent.
References:1. Leavitt JA, Campbell RJ.Cost-effectiveness in the diagnosis of sarcoidosis: the conjunctival biopsy.Eye. 1998;12 ( Pt 6):959-62.
2.Wertheim MS, Mathers WD, Suhler EB, Wilson DJ, Rosenbaum JT.
Histopathological features of conjunctival sarcoid nodules using noninvasive in vivo confocal microscopy. Arch Ophthalmol. 2005 Feb;123(2):274-6.
